With control of the Senate potentially on the line, next month’s runoff election between Senator Raphael Warnock, D-Ga., and Republican challenger Herschel Walker could set a spending record. According to OpenSecrets, a nonprofit that tracks money in politics, spending on the Walker vs. Warnock runoff already topped $260 million.

That figure ranks second among midterm races, trailing only the $372 million spent in this year’s Senate race between Sen.-elect John Fetterman, D-Pa., and Dr. Mehmet Oz. The most expensive race ever was the $515 million contest between former Sen. David Perdue, R-Ga., and Sen. Jon Ossoff, D-Ga. That race also went to a runoff, which Sen. Ossoff won.

“Just start adding zeroes and stop when you feel like it,” Chuck Clay, a former state Republican chair and former state senator, said. “Money is going to be no object on either side.”

Like with the Ossoff/Perdue race, a reason the Warnock/Walker runoff election could break a spending record is because the race could determine who controls the Senate for the next two years. As of Friday morning, Republicans held a 49-48 lead in the Senate, with Senate Races in Arizona and Nevada too close to call.

In the Arizona race, Sen. Mark Kelly, D-Ariz., leads Republican challenger Blake Masters. In Nevada, Sen. Catherine Cortez Masto, D-Nev., trails Republican challenger Adam Laxalt.

If those results hold, Walker will need to win the runoff in order for Republicans to win a majority. If he doesn’t, a 50-50 Senate with Vice President Kamala Harris breaking ties means Democrats keep the majority.

“Both parties have every incentive in the world to try and win,” Andrea Gillespie, an associate professor of political science at Emory University in Atlanta, said. “It’s going to be bare knuckles for the next month.”

Reuters contributed to this report.